Module Section System (MSS) with bayonet locking for 4'' enclosure tubes

Background

The Module Section System (MSS) is the second generation, now fully 3d printable module sections that fit the Blue Robotics 4'' enclosure tubes. The first generation was created for the AUV “Ålen” (The Eel). 

Me and two friends wanted a project to work on and what better than an autonomous underwater vehicle. This and the fact that me and my wife decided that turning a closet into an underwater robotics laboratory would be a great idea, here we are. Ålen is currently undergoing a static dive test program in our custom built test tank.

After first mounting all our hardware and electronics on continuous rails along the entire length of the enclosure, we soon realized that it would be much more manageable to divide everything into separate modules. These would then interlock with each other using the bayonet principle. We used multiple pin connectors for power and signals while miniature hydraulic quick connectors were used for fluids (ballast water). 

With the new MSS we wanted to build on our previous design and make the modules more accessible for others to use by making them fully 3d printable. We have improved the bayonet interlocking feature to make it more robust and reliable, and incorporated more features into the design.

Modules are great because they make team collaboration easy when the hardware can be distributed during development and testing. It also enables a high level of flexibility when being able to adapt the hardware within a system to various applications.

The Module Section System

The MSS consists of a male and a female mating ring, and four connecting rails.

Zip ties are used to join the connecting rails with the mating rings. This allows for a strong non-permanent joint without the need for high tolerances.

Locking design

The pegs on the male mating ring slides into slots on the female mating ring and the two modules are locked together with a twist and a click.

The locking rings also features mounting holes to attach it to the Blue Robotics 4'' O-ring Flange (WTE4-M-LOCKING-FLANGE)

Easy mounting of components

The connecting rails are shaped like DIN rails or “Top hat sections” (TS15 DIN section) which is perfect for mounting miniature terminal blocks that easily snaps into place. 

Spread throughout the length of the rails there are curved holes for zip ties to pass through. These can be used for easy cable management or for securing various components, as in the exemple below.

Customizable

The length of the connecting rails can be changed in the attached Step or SolidWorks files.

The files also contain a 3d printed mount that fits on the connecting rails. This in turn can be customized in CAD to fit any hardware one wish to mount in the module. 

Easy to print

All parts print without supports using PLA. I have used the following settings with good results:

Nozzle: 0.4mm

Layer height: 0.2 mm

Perimeters: 4

Infill: 35%

I'm sure materials such as PETG or ABS will work fine or even better, but going with the theme of accessibility it was developed using PLA.

Assembly instructions

Print one male mating ring, one female mating ring and four connecting rails.

Mount the connecting rails to the mating rings using eight zip ties. The bigger zip ties the better, but the head of the zip tie can be a maximum 8 mm wide.